Method of manufacturing an amorphous magnetic head

ABSTRACT

This disclosure is directed to an amorphous magnetic head which includes a main core having core halves each formed from non-laminated thin sheets of amorphous magnetic material, a non-magnetic spacer, with the core halves being abutted against each other through the non-magnetic spacer disposed in a head gap which is provided between the core halves and whose lower edge is defined by a coil winding opening formed in the core halves, and a set of reinforcing members applied onto opposite sides of the main core to hold the core halves between them. Resinous material is infiltered between the respective reinforcing members and the core halves for integration of the respective elements into one unit. The disclosure also relates to a method of manufacturing such an amorphous magnetic head on a large scale in an efficient manner.

This is a division of application Ser. No. 541,809, filed Oct. 13, 1983,now U.S. Pat. No. 4,697,217.

BACKGROUND OF THE INVENTION

The present invention generally relates to a head for recording a signalcontaining a high frequency component as in a television signal, onto arecording medium having a high coercive force or for reproducing such asignal therefrom, and more particularly, to an amorphous magnetic headin which a main core is composed of an amorphous magnetic material andalso, to a method of manufacturing such an amorphous magnetic head in anefficient manner.

Generally, in a magnetic head for a video tape recorder (VTR), ferritesingle crystal material is employed for a main core, because saidmaterial is superior in abrasion resistance, with favorable softmagnetic characteristics. Incidentally, owing to the recent trend towardcompact size of video tape recorders, there has been a tendency that amaterial such as a metal tape and the like having a high coercive forceand capable of achieving recording at a higher density is employed alsofor a magnetic tape, for example, as in the so-called 8 mm movie cameratype video tape recorders. Different from the conventional γ-Fe₂ O₃tape, such metal tapes have a high coercive force, and therefore, ifferrite materials having saturation flux densities in the range of 4000to 5000 gauss at most are adopted, the magnetic head is subjected tomagnetic saturation, and can not effect magnetization by overcoming thecoercive force of the metal tape. Accordingly, at present,investigations are made into the magnetic heads which employ Fe-Al-Sialloy (sendust) materials (saturation flux density Bs ≈8000 gauss),amorphous material (saturation flux density Bs ≈10,000 gauss), etc.having higher saturation flux densities as main cores, of which thesendust heads have already been supplied into the market as audio headscorresponding to metal tapes. However, the sendust heads as referred toabove have various disadvantages for the heads of video tape recordersto be used in a higher frequency range (e.g. 5 MHZ or thereabout) inthat machining thereof is difficult, while due to a low electricalresistance as compared with the ferrite material, the sendust heads havea large eddy current loss at high frequency range, with a sharpreduction of the effective permeability, and thus, the sendust headshave not been supplied as yet into the market for the heads of videotape recorders currently available.

On the other hand, with respect to the amorphous magnetic head, althoughattention has recently been directed to the amorphous material itself(during the past five years at most) as a future magnetic material fordevelopment both in Japan and abroad, the amorphous magnetic heads havenot yet been put into practical application at the current stage.

As is well known, the amorphous material is obtained by a manufacturingmethod referred to as a liquid melt rapid cooling method, in which anamorphous material having an alloy composition not conceivable by theconventional knowledge of metallurgy may be produced in terms ofprinciple. On the contrary, there is a limitation to the configurationsof the material to be produced by the above manufacturing method. Morespecifically, since it is required to rapidly cool the molten metal atcooling speeds of 100,000° to 1,000,000° C./sec., the resultantamorphous material is obtainable only in the form of a ribbon-like sheetof 10 to 100 microns in thickness or in the form of a powder.

Accordingly, in the amorphous magnetic material, it is not possible toemploy, as it is, the manufacturing method conventionally adopted forthe ferrite material, i.e., the processing technique such as cutting,polishing, welding, etc. from a bulk material. However, in the casewhere the conventional manufacturing method as described above is to befollowed somehow, it may be considered to employ a starting materialprepared by laminating a large number of ribbon-like sheets one uponanother (i.e., forming such ribbon-like sheets into a shape, similar tothe bulk material), thereby to constitute a magnetic head with a trackwidth less than a thickness of the ribbon-like sheet, but since precisecontrol of a thickness of a bonding material layer between theribbon-like sheets can not be readily effected, it is extremelydifficult to arrange the confronting core halves to face each otherprecisely.

Moreover, as a problem inherent in the amorphous material, there is theproblem related to crystallization temperature Tx. Generally, amorphousmaterials prepared by the rapid cooling method have transition points ofcrystalline structure referred to as vitrification temperature Tg andcyrstallization temperature Tx. In connection with the above, thevitrification temperature is a temperature at which the amorphousmaterial begins to be softened in the similar manner as in the commonsoda-lime glass, silica glass, etc., while the crystallizationtemperature is a temperature at which the amorphous structure istransferred to the crystalline structure. It is to be noted here that,different from glass in general, the amorphous material is not providedwith reversibility during passing of the above transition points. Inother words, once the amorphous structure has been turned into thecrystalline structure, it will never be returned into the originalamorphous state. Accordingly, for manufacturing magnetic heads with theuse of such amorphous material as described above, it is not possible toapply thermal or mechanical energy exceeding the crystallizationtemperature Tx, while processing techniques such as glass welding,brazing, etc. for the conventional ferrite material, sendust material,etc. can not be applied, thus making it necessary to develop newprocessing and manufacturing techniques.

SUMMARY OF THE INVENTION

Accordingly, an essential object of the present invention is to providea magnetic head having a main core made of thin sheets of an amorphousmagnetic material, i.e., an amorphous magnetic head, which is capable ofefficiently recording high frequency signals such as video signals, etc.on a high coercive tape such as a metal tape, with a simultaneousprolongation of life.

Another important object of the present invention is to provide anamorphous magnetic head of the above described type, which is stable infunctioning at high reliability, and can be readily manufactured at lowcost.

A further object of the present invention is to provide a method ofmanufacturing an amorphous magnetic head of the above described type inan efficient manner on a large scale.

In accomplishing these and other objects, according to one preferredembodiment of the present invention, there is provided an amorphousmagnetic head which includes a main core having core halves each formedfrom non-laminated thin sheets of amorphous magnetic material, anon-magnetic spacer, said core halves being abutted against each otherthrough the non-magnetic spacer disposed in a front gap which isprovided between said core halves and whose lower edge is defined by acoil winding opening formed in the core halves, and a set of reinforcingmembers applied onto opposite sides of the main core to hold the corehalves therebetween, with resinous material being filled between therespective reinforcing members and the core halves for integration ofthe respective elements into one unit.

The amorphous magnetic head of the present invention as described abovemay be produced by a manufacturing method which includes the steps ofconstituting a set of core halves each having a coil winding openingwhich defines a lower edge of a head gap at least in one of the abuttedfaces thereof through processing of thin sheets of amorphous magneticmaterial without lamination thereof, arranging the core halves to beabutted against each other through a non-magnetic spacer disposed at thefront gap between said core halves, holding the core halves thus abuttedagainst each other between a set of reinforcing members, and fillingresinous material through penetration between the core halves and thereinforcing members under a state where both of said core halves aredepressed from all directions, i.e., both vertically and laterally, forsubsequent heating and curing of the resinous material, thereby tointegrate the respective elements into one unit.

By the arrangement and steps according to the present invention asdescribed above, anamorphous magnetic head highly efficient in use hasbeen advantageously presented.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome apparent from the following description taken in conjunction withthe preferred embodiment thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is a perspective view, partly broken away, of an amorphousmagnetic head according to one preferred embodiment of the presentinvention;

FIGS. 2(a) and 2(b) are a top plan view and a front elevational view ofthe magnetic head of FIG. 1;

FIG. 3 is a flow-chart for explainirg a manufacturing process of themagnetic head of FIG. 1;

FIG. 4 is a fragmentary top plan view of an amorphous ribbon to beemployed in the manufacture of the magnetic head of FIG. 1;

FIG. 5 is the fragmentary top plan view of the amorphous ribbon of FIG.4 after etching,

FIGS. 6(a) and 6(b) are perspective views showing states in which corechips prepared from the amorphous ribbon of FIG. 5 are accommodated injigs;

FIGS. 7(a) and 7(b) are views similar to FIGS. 6(a) and 6(b), whichparticularly show the states after grinding;

FIG. 8 is a view similar to FIGS. 7(a) and 7(b), which particularlyshows provision of a spacer;

FIG. 9 is an exploded perspective view of the magnetic head of FIG. 1before assembly;

FIG. 10 is a side elevational view of the magnetic head of FIG. 9 asassembled;

FIG. 11 is a view similar to FIG. 10 explanatory of combination ofrespective elements into one unit by a resinous material;

FIGS. 12(a) and 12(b) are a top plan view and a front elevational viewof the magnetic head as released from a jig;

FIGS. 13, 14(a) and 14(b) are perspective views of magnetic headsaccording to modifications of the present invention;

FIGS. 15 and 16 are a side elevational view and a perspective view forexplaining a modified method of manufacturing an amorphous magnetic headaccording to the present invention;

FIG. 17 is a side elevational view similar to FIG. 15 for explaininganother modified method of manufacturing an amorphous magnetic head ofthe present invention;

FIGS. 18 and 19 are a side elevational view and a perspective viewsimilar to FIGS. 15 and 16 for explaining still another modified methodof manufacturing an amorphous magnetic head according to the presentinventon;

FIGS. 20 and 21 are a perspective view and a side elevational view of anamorphous magnetic head according to another modification of the presentinvention;

FIG. 22 is a flow-chart for explaining a manufacturing method of anamorphous magnetic head according to a further modification of thepresent invention;

FIG. 23 is a fragmentary top plan view of an amorphous ribbon to beemployed in the modified manufacturing method of FIG. 22;

FIG. 24 is a fragmentary top plan view of the amorphous ribbon of FIG.23 after etching;

FIGS. 25 and 26 are fragmentary perspective views of a number of seriesof core halves as accommodated in a jig for explaining grinding processof confronting surfaces of the core halves;

FIG. 27 is a view similar to FIG. 26, which particularly shows theprocess for providing spacers;

FIG. 28 is a fragmentary top plan view for explaining a temporary fixingprocess of first and second series of core halves;

FIG. 29(a) is a fragmentary top plan view for explaining a joiningprocess of reinforcing members and cores; and

FIG. 29(b) is a side sectional view taken along the lineXXIX(b)--XXIX(b) in FIG. 29(a).

DETAILED DESCRIPTION OF THE INVENTION

Before the description of the present invention proceeds, it is to benoted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

Referring now to the drawings, there is shown, in FIGS. 1 to 2(b), anamorphous magnetic head HA according to one preferred embodiment of thepresent invention. The magnetic head HA generally comprises a main corec which includes core halves 11 abutted against each other and eachformed by shaping non-laminated thin plates or sheets (24 microns inthickness) of an amorphous magnetic material, a pair of reinforcingmembers 18 for holding the main core c therebetween, and layers b of abonding material (less than 2 microns in thickness) each applied betweenthe main core c and the reinforcing member 18 so as to be cured orhardened. Each of the core halves 11 is formed with a notch or groove gas a coil winding opening between the abutted faces thereof, while aspacer 17 of a non-magnetic material for forming a front, gap isprovided at the upper portion of the groove g. Each of the reinforcingmembers 18 made, for example, of glass material is formed with athrough-hole o in a position corresponding to the groove g or coilwinding opening of the main core c so as to make it possible to effectthe so-called balance winding of the coils (not particularly shown)therethrough.

The magnetic head HA is ground for providing a predetermined radius ofcurvature on its contact face f confronting a magnetic tape (not shown)so as to achieve a proper matching with respect to the magnetic tapeduring running of said magnetic tape.

Meanwhile, since the magnetic head HA is extremely small in size withdimensions of about 3 mm square and several hundred microns inthickness, the side faces of the reinforcing members 18 are connected toa head base (not particularly shown), with the contact face f of thehead HA being projected from said head base for easiness in handling.

The magnetic head HA according to the present invention which is formedby arranging the core halves 11 made of non-laminated thin sheets of theamorphous magnetic material to be abutted against each other, andapplying the reinforcing members 18 of glass material to opposite sidesof the core halves 11, with infiltration of resin or bonding agent btherebetween for the formation of the entire structure into one unit,can be manufactured at a high yield.

Referring further to a flow-chart of FIG. 3 and also, to FIGS. 4 to 11illustrating states of processings at respective steps, the outline ofthe method of manufacturing the magnetic head according to the presentinvention will be explained hereinbelow.

In the first place, a thin sheet or ribbon 10 of the amorphous materialapproximately 24 microns or so in thickness is prepared by the liquidmelt rapid cooling method as described earlier (FIG. 4), and a series ofcore halves 11 of a required shape are formed in the above ribbon 10 bya chemical etching (FIG. 5), with a through-opening for the groove gbeing formed in each of the core halves 11 for winding the coiltherethrough. The series of core halves 11 thus prepared are cut offalong dotted lines n to obtain a large number of core halves or corechips 11. As shown in FIGS. 6(a) and 6(b), the core chips 11 areaccommodated as a stack in a jig Ja so that the through-openings arearranged in a forward position at one side, and in a rearward positionat the other side, and are first subjected to rough grinding so as toremove sagging and the like by the etching for setting the core halves11 into the predetermined dimensions. Subsequently, the front gapforming face of the magnetic head is ground through employment of veryfine grinding grains and a grinding machine. FIGS. 7(a) and 7(b) showthe states upon termination of the above grinding.

In the above case, an angle 16 for accommodating the stacked core halves11 with respect to a wall surface 15 of the jig Ja (FIG. 6(b)) isarranged to coincide with an azimuth angle of the magnetic head.

The core chips 11 ground as described above are detached from the jig Jafor a heat treatment, which is intended to remove stresses due to rapidcooling and mechanical processing during manufacture of the amorphousmaterial, and also, to eliminate a grinding strain imparted during theabove grinding process. Generally by applying such heat treatment, thepermeability of cores may be improved, because a weak magneticanisotropy actually remains in the lengthwise and widthwise directionsof the ribbon of amorphous material due to temperature gradient andmechanical stress during the rapid cooling of the ribbon, although theamorphous material having no crystalline structure should normally befree from crystalline anisotropy in terms of principle. In the aboveembodiment, since the amorphous material employed is of metal metalloidseries (75% of Fe, Co series, 25% of semi-metals such as Si, B, P andC), with Curie temperature Tc at 450° and crystallization temperature Txat approximately 500° C., the temperature is raised to the vicinity of apoint below Curie temperature Tc and the heat is effected in themagnetic field (especially, rotating magnetic field).

Subsequently, as shown in FIG. 8, the large number of core chips 11 aregain stacked within the jig Ja, and a spacer 17 of non-magnetic materialas SiO₂, TiN, SiN, WN or the like is formed on the surf equivalent tothe front gap by a predetermined gap length (for example, 0.4 to 0.05micron) through vapor deposition or ion plating. It may be so arrangedthat the predetermined gap length is covered through combination withother core halves.

Thereafter, as shown in FIG. 9, a set of core halves 11 and separatelyprepared reinforcing members 18 of glass material are disposed betweensheets Jb, for example, of Teflon as a jig, and the core halves 11 aredepressed from opposite sides by forces F1 of 1 to 100 grams as shown inFIG. 10, while the whole structure is vertically depressed by forces F2through sheets Jb. For facilitation of depression of the core halves 11as described above, for example, by a jig Jc (FIG. 11), each of the corehalves 11 is arranged to laterally project from the reinforcing member18 to a certain extent.

With the depressed state as described above maintained, the wholestructure of the magnetic head is impregnated with epoxy resin in thevacuum state, with a subsequent hardening or curing through heating (byleaving to stand at a temperature of 100° C. for 60 to 90 minutes), andthus, the reinforcing members 18 and core halves 11 are combined intoone unit together with depressing jig Jc between the sheets Jb as shownin FIG. 11. After curing of the epoxy resin, the structure thus isreleased from the sheets Jb and jig Jc (FIGS. 12(a) and 12(b)) and isproperly shaped for its tape contacting face or the like with furtherprovision of coils, etc., and thus, the magnetic head as shown in FIG. 1is obtained.

The material for the sheets Jb is not limited to ethylene tetrafluorideor trifluoride (e.g. Teflon) as described above, but may be replaced byany material such as polyethylene, polypropylene or the like so far asit can be utilized as a solid releasing material to which epoxy resindoes not adhere. However, releasing material in a liquid form is notsuitable for the purpose, since it tends to penetrate into gap portionsof the head or between the reinforcing members and cores for undesirablereduction of the bonding strength therebetween.

Moreover, it is preferable that the reinforcing members 18 areconstituted by a dense material of a non-magnetic and non-conductivenature such as ceramics, etc. besides glass as described earlier,because a sintered material having air bubbles or voids therein tend tobe subjected to clogging by the magnetic particles from the magnetictape, thus resulting in an increased spacing loss. Forming thereinforcing members 18 by a metallic material is not preferable, sincerecording efficiency is extremely reduced by an anti-magnetic fieldproduced in the metallic reinforcing members during the recording, butis suitable for a magnetic head exclusive for reproduction, because suchmetallic reinforcing members function to improve reproducing efficiencyduring the reproduction.

Referring to FIGS. 13 and 14(b), there are shown modifications of themagnetic head HA as described so far. In the modified magnetic head HBof FIG. 13, the reinforcing members 18B made of a metallic material hascoil winding portions 18B-1 of non-metallic material as indicated byhatchings, while in the modified magnetic head HC of FIG. 14(a), thereinforcing members 18C made of a metallic material also have coilwinding portions 18C-1 of non-metallic material as shown by hatchings.The magnetic heads HB, and HC of the above described type may be used asheads both for recording and reproduction. In another modified magnetichead HC' in FIG. 14(b), the reinforcing members 18C' are made of amagnetic ferrite material, while the portion 18C'-1, at leastcorresponding to the spacer 17 should be made of a non-magneticmaterial, for example, glass in order to prevent magneticshortcircuiting. In connection with the above, it is to be noted that,in a laboratory experiment, required reproduction output of the magnetichead may be obtained even when the reinforcing members are entirely madeof a glass material, but considerable care and attention are requiredfor the processings. When the reinforcing members are constructed in themanner as described above with reference to FIGS. 13, 14(a) or 14(b),the reproduction output of the magnetic head can be readily improved.Since other constructions and effects of the magnetic heads HB, HC andHC' are generally similar to those of the magnetic head HA of FIG. 1,detailed description thereof is abbreviated for brevity.

As is clear from the foregoing description, according to the presentinvention, it is so arranged that core halves formed into thepredetermined shape from the amorphous magnetic thin materialmanufactured by the liquid melt rapid cooling method, withoutfundamentally effecting the processing in the direction of thickness ofsaid amorphous material, are abutted against each other, while thereinforcing members are further applied to the core halves from oppositesides thereof, with resin being filled therebetween to be hardened forintegration of the magnetic head structure, and therefore, magneticheads for high frequency range having the main cores of amorphousmagnetic material superior in magnetic characteristics may bemanufactured at a favorable yield in production.

Referring further to FIGS. 15 and 16, there is shown a modified methodof manufacturing an amorphous magnetic head. In this modification, thejigs Jb and Jc, etc. described as employed for keeping the core halves11 in pressure contact with each other together with the reinforcingmembers 18 for the formation of the head gap in the foregoingembodiments are replaced by a resilient spring frame S made, forexample, of non-magnetic metal or resinous material, and formed bychemical etching or blanking through processing by a machine to have asize just sufficient to accommodate therein an assembly of the corehalves 11 and reinforcing members 18.

More specifically, as shown in FIG. 15, the resilient spring frame S isprovided with side portions S-1 having projections p for depressing thecore halves 11. With said side portions S-1 slightly opened outwardly atupper ends thereof, and the frame S is fitted around the assemblyincluding the core halves 11 abutted against each other through thenon-magnetic spacer 17 and held between the reinforcing members 18 asdescribed previously, with the bonding material b' being applied betweenthe side edges of said assembly and the inner edges of the frame S,whereby the core halves 11 are pressed against each other at theprojections p by the spring force of theside portions S-1 in thedirections shown by arrows to provide the amorphous magnetic head HD asshown in FIG. 16.

After completion of the assembling of the magnetic head, the frame S maybe removed from the magnetic head or left as it is on the magnetic headdepending on necessity.

By the above modified method, the jigs required for the manufacture ofthe amorphous magnetic heads may be dispensed with for thesimplification of the manufacturing process.

In another modified method as shown in FIG. 17, the frame SB made, forexample, of a metallic material having a resiliency such as phosphorbronze, stainless steel, etc. has its one side portion SB-1 cut off atone end and provided with a projection p so as to act as a spring foreffecting abutting of the core halves 11 (i.e. formation of the headgap) by the resilient restoring force of said side portion SB-1. In thiscase also, the frame SB may be removed or left as it is after completionof the magnetic head, but if the frame SB is to be left on the magnetichead as in the arrangement of FIG. 16, non-magnetic material should beused for the frame SB.

In still another modified method as illustrated in FIGS. 18 and 19, theframe SC with a continuous side portions has a protrusion pc formed inone side portion SC-1 thereof as shown. For use, the frame SC is fittedaround the assembly including the core halves 11 and the reinforcingmembers 18, and the protrusion pc is pushed inwardly in a directionindicated by an arrow in FIG. 18 by a depressing plate Ta, with theframe SC being supported at the other side by a support plate Tb forabutting the core halves 11 against each other by depressing one of thecore halves 11 at the protrusion pc so as to form the head gap. Afterimpregnation of the bonding material b' and subsequent curing in themanner as described earlier, the magnetic head thus assembled issubjected to formation of the predetermined radius of curvature at thetape contact surface f and depth adjustment to provide a finishedmagnetic head HD' as shown in FIG. 19. For the convenience in the coilwinding, the frame should preferably be of non-magnetic material, but inthe case where the frame is to be detached from the magnetic head afterimpregnation of the bonding material b and subsequent curing thereof,the frame need not necessarily be of non-magnetic material.

By the employment of the frames according to the present invention asdescribed so far with reference to FIGS. 15 to 19, positioning of theamorphous core halves and reinforcing members during assembly of themagnetic head has been facilitated, and furthermore, by preventing corehalves from rotation during abutting thereof, it becomes possible tostably obtain favorable head gaps, with a consequent improvement of theyield in the abutting step in the manufacture of the magnetic heads.

In FIGS. 20 and 21, there is shown another modification of the amorphousmagnetic head of FIG. 1.

In the modified amorphous magnetic head HE of FIGS. 20 and 21, the corehalves 11 abutted against each other through the non-magnetic spacer 17and held between the reinforcing members 18 are formed into one unitwith said reinforcing members 18 by partially fusing the core halves 11,instead of employing the resinous material b for integration as in themagnetic head HA of FIG. 1.

More specifically, as shown in FIGS. 20 and 21, the magnetic head HEincludes, for example, welded portions w disposed at corresponding fourcorner thereof. These welded portions w may be formed by directing laserbeams from laser beam sources (not particularly shown) into the assemblywhich includes the core halves 11 abutted against each other through thenon-magnetic spacer 17 so as to be held between the reinforcing members18, and which is depressed both in the vertical and lateral directionsas described earlier. In other words, the laser beams pass through thereinforcing members 20 of transparent glass material so as to beconverted into heat on the surface of the core halves 11 made of theamorphous magnetic material for fusing corresponding portions thereof.Thereafter, upon interruption of the laser beam irradiation, the corehalves 11 and the reinforcing members 18 contacting said core halves 11are welded together during solidification of the molten material. Byeffecting the operations as described above successively orsimultaneously at the respective corner portions on the opposite facesof the main core c having the core halves 11, the integration of themain core c with the reinforcing members 18 is completed. The size ordiameter of each of the welded portions w may be set approximately inthe range of 1 to 2 microns.

Referring further to FIGS. 22 to 29(b), still another modification ofthe method of manufacturing the amorphous magnetic head according to thepresent invention, which is particularly suited to mass production, willbe explained hereinbelow.

Firstly, the ribbon 10' of the amorphous material approximately 24microns or so in thickness is prepared by the liquid melt rapid coolingmethod in the similar manner as described earlier (FIG. 23), and a firstseries 11A of core halves 11 of a required shape are formed in the aboveribbon 10' by the chemical etching (FIG. 24), with the through-openingfor the groove g being formed in each of the core halves 11 for windingthe coil therethrough. The first series 11A of core halves 11 thusprepared is shown in the state before the surface 11f thereofcorresponding to a second series 11B of core halves 11 to be describedlater is formed through cutting, and includes the plurality of corehalves 11 and connecting portions 11c which are alternately provided,with a width d1 of each connecting portion 11c being arranged to besufficiently larger than a width d2 which is to be cut off duringformation of the surface 11f.

As shown in FIG. 25, many first series 11A of core halves 11 asdescribed above are stacked in the direction of thickness so as to beaccommodated in the jig Ja' and are first subjected to rough grinding soas to remove sagging and the like due to the etching for setting thecore halves 11 into the predetermined dimensions. Subsequently, thefront gap forming face 11g thereof is ground through employment of veryfine grinding grains and a grinding machine. It is to be noted that theaccommodating angle 16 of the first series 11A of core halves 11 withrespect to the wall face of the jig Ja' is adapted to coincide with theazimuth angle in the similar manner as described earlier with referenceto FIG. 6(b). FIG. 26 shows the state upon termination of the grinding.

Each of the series 11A of core halves 11 ground as described above isdetached from the jig Ja' for the heat treatment in the manner asdescribed earlier with reference to the first embodiment of FIGS. 1 to12(b).

Subsequently, as shown in FIG. 27, the large number of the series ofcore halves 11 are again stacked within the jig Ja', and the spacers 17of non-magnetic material such as SiO₂, TiN, SiN, WN or the like areformed on the surface 11g equivalent to the front gap by a predeterminedgap length for example, 0.4 to 0.05 micron) through vapor deposition orion plating. It may be so arranged that the predetermined gap length iscovered through combination with other core halves in the similar manneras in the previous embodiment.

Thereafter, as shown in FIG. 28, the first stack 11A and the secondstack 11B of core halves 11 are disposed so that the front gap formingsurfaces 11g and the coil winding openings g of the respective stack 11Aand 11B coincide with each other, and abutted against each other throughdepression by the jig Jb'. In the above state, laser beams areirradiated onto both of the stack 11A and 11B of core halves 11 so as tobridge the respective connecting portions 11c by welding therebetween toeffect temporary connection as indicated at the spots w.

In the next step, as shown in FIGS. 29(a) and 29(b), the stack 11A and11B of the core halves 11 temporarily combined with each other asdescribed above are held between the reinforcing members 18' having thethrough-openings o corresponding to the coil winding openings g so thatthe openings o confront the openings g, and epoxy resin is impregnatedbetween the stacks 11A and 11B of the core halves 11 and the respectivereinforcing members 18' in the vacuum state for heat curing by beingleft to stand for 60 to 90 minutes at 100° C. In FIG. 29(b), the layersof epoxy resin or bonding material thus formed are represented by "b".

In the manner as described above, the respective stacks 11A and 11B ofthe core halves 11 are bonded to the reinforcing members 18' forintegration therewith.

Subsequently, as shown by dotted lines L1 in FIG. 29(a), the assemblythus obtained is cut off into individual chips of magnetic heads, whosecontact surfaces with respect to the magnetic tape are ground for aproper radius of curvature matched with the magnetic tape as indicatedby dotted lines L2 so as to provide a required gap depth.

By the method as described so far, the amorphous magnetic head, forexample, as shown in FIG. 1 may be manufactured in an efficient manneron a large scale.

In the above manufacturing method of FIGS. 22 to 29(b), since it is soarranged that one set of the stacks of core halves are temporarilyconnected to each other by welding the connecting portions forconnecting the plurality of core halves so as to be bonded to thereinforcing members in such a state, the depression in the direction topush the core halves to each other is not required during the bonding,with the depression only from the side of the reinforcing members, i.e.in the vertical two directions sufficiently serving the purpose, thusresulting in a facilitation of bonding work and consequently, in animproved efficiency for the mass production of the magnetic head.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to be notedhere that various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention, theyshould be construed as included therein.

What is claimed is:
 1. A method of manufacturing an amorphous magnetichead, comprising the steps of:a first step of processing a sheet ofamorphous magnetic material to form a sheet having a plurality ofinterconnected core halves in which each core half has a coil windingopening and a head gap face extending along an edge of said core halffrom one side of said coil winding opening; a second step of formingindividual core halves by appropriately cutting said sheet of corehalves after the completion of said first step and stacking a pluralityof said core halves; a third step of grinding opposing faces, includingsaid head gap faces, of said plurality of said plurality of core halvesto have a predetermined azimuth angle after the completion of saidsecond step, thereby forming a head gap, between opposing head gapfaces, and having said predetermined azimuth angle and thereafterapplying a non-magnetic spacer into said head gap and arranging at leasta pair of said stacked core halves to that said opposing faces arebutted against each other; and a fourth step of applying reinforcingmembers under pressure onto opposite side faces of said core halves,with the opposing head gap faces of the pair of core halves facing eachother through said non-magnetic spacer after the completion of saidthird step, and then impregnating a resinous bonding agent between thepair of core halves and the reinforcing members, thereby to integratethe pair of core halves and said reinforcing members into one unit suchthat a magnetic gap is formed therein at said head gap.
 2. A method ofmanufacturing an amorphous magnetic head, comprising the steps of:afirst step of processing sheets of amorphous magnetic material to formsheets having a plurality of interconnected core halves in which eachcore half has a coil winding opening and a head gap face extending alongan edge of said core half from one side of said coil winding opening,and which said core halves are longitudinally arranged in one row oneach sheet through connecting portions and stacking a plurality of saidsheets; a second step of grinding opposing faces, including said headgap faces, of said core halves of said plurality of sheets to have apredetermined azimuth angle, after completion of said first step,thereby forming a head gap, between opposing head gap faces of said corehalves of said plurality of sheets, and having said predeterminedazimuth angle, and thereafter applying a non-magnetic spacer into saidhead gap; a third step of causing the opposing head gap faces of theplurality of sheets of said core halves to face each other underpressure through said non-magnetic spacer, such that said core halves ofsaid sheets and the connecting portions are aligned, after completion ofsaid second step, and then spot welding the connecting portions of theplurality of the sheets to each other, thereby to form the core sheetsin which all of said sheets of the core halves are temporarily combinedinto one unit; a fourth step of joining reinforcing members ontoopposite side faces of said core sheets so as to bridge the core halvesof the plurality of sheets after completion of the third step; and afifth step of cutting off the spot-welded connecting portions of saidcore sheets after completion of said fourth step to form a plurality ofhead chips into which opposing core halves are formed into one unit bysaid reinforcing member.
 3. The method of claim 1, wherein said grindingstep includes positioning a plurality of said core halves in a jig, suchthat all core halves face the same direction and said opposing faces areexposed for the grinding step, and further wherein said core halves arearranged at said predetermined azimuth angle, so that all of said corehalves may be polished to have said predetermined azimuth angle in asingle step.
 4. The method of claim 2, wherein said grinding stepincludes positioning said sheets in a jig, such that all core halvesthereof are aligned and face the same direction and wherein saidopposing faces are exposed for the grinding step, and further whereinsaid sheets are arranged at said predetermined azimuth angle, so thatall of said core halves may be polished to have said predeterminedazimuth angle in a single step.
 5. A method as claimed in claim 1,wherein said fourth step includes a pressing means for fitting a framearound an assembly including the core halves and the reinforcing membersfor abutting the core halves against each other for the formation of themagnetic gap.
 6. A method as claimed in claim 5, wherein said frame isprovided with projection means for depressing said core halves.
 7. Amethod as claimed in claim 5, wherein said frame is made of a resilientmaterial having a spring force so as to depress the core halves by aresilient restoring force thereof.